1. Field of the Invention
The present invention relates to a method of producing a sheet steel product by heating a sized steel sheet, hot forming the steel sheet in a pair of tools and hardening the formed product by cooling it rapidly from an austenitizing temperature while it is still in the pair of tools and then machining the product.
2. Background of the Invention
This method of making hardened sheet steel products is known from GB-149035-A incorporated herein by way of reference and it is called press hardening. A great advantage is that hardened products with complicated form can be produced and still, the tolerances in form and size can be narrow.
In order to reach very high position accuracy of some details, for example holes, slots and the like, a machining operation is carried out on the hardened product. This machining causes high tool wear and may cause reduced fatigue resistance.